Since its proposal in Internet Engineering Task Force (IETF) Request for Comments (RFC) 3588, the Diameter protocol has been increasingly adopted by numerous networked applications. For example, the Third Generation Partnership Project (3GPP) has adopted Diameter for various policy and charging control (PCC), mobility management, and IP multimedia subsystem (IMS) applications. As IP-based networks replace circuit-switched networks, Diameter is even replacing SS7 as the key communications signaling protocol. As networks evolve, Diameter is becoming a widely used protocol among wireless and wireline communications networks.
One significant aspect of the Diameter protocol is Diameter packet routing. Entities referred to as Diameter routing agents (DRAB) facilitate movement of packets in a network. In various deployments, DRAs may perform elementary functions such as simple routing, proxying, and redirect.